The Cell Theory

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The Cell Theory
Hairy T-cell
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Definition

• Three part theory about cells
• 1. All living things are made of cells.

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Part 2 of the Theory

• 2. The cell is the basic structural and
  functional unit of life.

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Part 3 of the Theory

• 3. All cells come from pre-existing cells.

yeast cells dividing
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Who came up with this theory?
All plants are made of cells!

• 1. Schleiden (circa 1838)

Onion skin cells
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Who came up with this theory?
All animals are made of cells!

• 2. Schwann

Human red blood cells
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Who came up with this theory?

• 3. Virchow

All cells come from pre-existing cells!
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How big are cells?

• Microscopic (mostly)
• Measured in microns µm
• (micrometers).
• A µm is one millionth of a meter
• 10-9 m one thousandth of 1 mm.

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How big are cells?

• Smallest free-living cell
• Mycoplasma genitalium
• Size 0.2 to 0.3 µm

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How big are cells?

• Bacteria e.g. Eschericia coli (aka E.coli)
• Size1 µm by 3 µm

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How big are cells?

• Human red blood cell 8 µm in diameter

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How big are cells?

• Largest cell on the human body
• ovum
• Size
• 1000 µm in diameter
• (1 mm)

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How big are cells?

• Smallest cell in the human body
• sperm cell.

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How big are cells?

• Largest cell with a metabolism
• Chaos chaos
• Size1-5 mm in length.
• common name
• Giant Amoeba

Chaos diffluens, is an amoeba closely related to
the giant amoebae
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How big are cells?

• Largest cell yolk of an ostrich egg

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Ostrich, egg, humans
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Ostrich emerged from egg
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How can we study cells?

• Problem
• They are microscopic!
• Solution
• Use a microscope!

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Types of Microscopes

• Compound light microscope
• Light passes through lenses to magnify image up
  to 1000X
• Can observe living cells

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Types of Microscopes

• 2. Electron microscope
• Uses a beam of electrons to magnify image
• gt 1000X
• Kills cells being observed

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Common features of all cells

• Small size allows materials to move via
  diffusion
• Diffusion process by which molecules move from
  levels of high concentration to levels of low
  concentration until equilibrium is reached

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Diffusion

• Google Image Result for http//www.indiana.edu/ph
  ys215/lecture/lecnotes/lecgraphics/diffusion.gif

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Common features of all cells

• 1. Cell Membrane selectively/differentially
  permeable (lets some things in and out)

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Common features of all cells

• 2. Cytoplasm semi-fluid material in which cell
  organelles float

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Common features of all cells

• 3. Nucleic acid containing genetic code
• Which nucleic acid?
• DNA

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Common features of all cells

• 4. Cytoskeleton proteins that support the cell
• (Microtubules
• microfilaments)

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Common features of all cells

• 5. Ribosomes
• make proteins

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If Cells could be really big
Star Trek - The Immunity Syndrome
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Bibliography

• http//www.hotlinecancer.com/?cat28
• http//news.bbc.co.uk/1/hi/sci/tech/4636121.stm
• http//www.thebacteriabusters.com/eColi.html
• http//www.lungcancer.co.uk/how.htm
• http//www.fi.edu/learn/heart/blood/red.html
• http//biology.about.com/library/weekly/aa091400a.
  htm
• http//www.pbs.org/wgbh/amex/babies/peopleevents/e
  _ovum.html
• http//www.dkimages.com/discover/Home/Animals/Bird
  s/Growth-and-Development/Ostrich/Ostrich/Ostrich-1
  5.html
• http//www.flickr.com/photos/71751551_at_N00/12623291
  63/
• http//commons.wikimedia.org/wiki/ImageOstrich_eg
  g.jpg
• http//www.mambalam.net/slideshow.php?set_albumNam
  eAnimalia
• http//strangebenevolent.blogspot.com/2007/07/meer
  kats-and-ostriches.html
• www.madsci.org/posts/archives/dec97/878139903.Cb.r
  .html
• http//en.wikipedia.org/wiki/Amoeba_proteus
• http//en.wikipedia.org/wiki/The_Immunity_Syndrome
  _(Star_Trek

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Bibliography

• http//www.pacpress.com/level3/micron.htm
• Google Image Result for http//www.indiana.edu/ph
  ys215/lecture/lecnotes/lecgraphics/diffusion.gif
• http//commons.wikimedia.org/wiki/ImageDiffusion.
  jpg
• http//library.thinkquest.org/C004535/cell_membran
  es.html
• http//sun.menloschool.org/cweaver/cells/e/riboso
  mes/
• http//www.elmhurst.edu/chm/vchembook/580DNA.html
  
• http//sciencecity.oupchina.com.hk/biology/student
  /glossary/cytoplasm.asp
• http//www.uic.edu/classes/bios/bios100/lecturesf0
  4am/lect06.htm